1. Field of Invention
The invention concerns a seat heater with an electric conductive sheet-type heating element made of flexible high-resistivity material to which the main electrodes for heating the sheet-type heating element are connected.
2. Description of the Background Art
An overall high level has been achieved in the design of seat heaters. Several technologies are available that ensure even warming of the seat. For example, the strand technology has been employed very successfully since heat output can be set within a wide range with this design. Additionally, the heat output can be adjusted to the seat's geometry. Due to the complex production procedure, however, this technology is increasingly limited to special applications.
Recently, a textile sheet-type heating element on carbon basis has been employed as the conductive sheet-type heating element for seat heaters; apart from the benefit of increased mechanical comfort, this technology also guarantees very homogeneous distribution of thermal output due to its design.
With the help of these known seat heaters, it is possible to warm seats very homogeneously so that a comfortable heat temperature is achieved after a heating phase and no differences in temperature arise that could be felt on the seat. With the seat's thermal capacity being a given value, these known seat heaters unfortunately do not allow this condition to be achieved quickly due to limitations of the heater's overall power requirements. The seat's thermal connection with the passenger additionally creates the basic problem of the passenger contributing to the warming process of the cold seat in the initial phase to a relatively large extent and thus reinforcing the perception of coldness. In this respect, existing seat heaters do not keep the passenger completely away from unpleasant influences and are therefore insufficient. Furthermore, we can proceed on the assumption that during the time that the driver perceives his seat as being cold a reduction in his ability to concentrate occurs. The problem of the delayed warming process can certainly be described as the largest weakness of existing seat heaters since the need for a seat heater is directly connected to the fact that the seat should warm up faster, from heat made available by the motor, compared to the much slower warming of the vehicle's interior.